1. Field of the Disclosure
The present disclosure relates generally to image forming devices and more particularly to methods and devices to control toner concentration in an image forming device.
2. Description of the Related Art
Dual component development (DCD) electrophotography printing systems utilize a developer mixture of toner and magnetic carrier in the printing process. Multiple strategies have been employed to control the toner concentration in this mixture with varying levels of success. One method is to utilize a toner concentration sensor that measures the magnetic permeability of the developer mix. As the toner concentration decreases, the magnetic permeability of the mixture increases, which changes the sensor output voltage. A control system adds toner to the mixture to maintain the sensor output voltage at a given set point. An alternative method for controlling toner concentration is to count the number of individual pixels imaged, computing the toner volume consumed, and replenishing toner in the mixture based on this computation.
The traditional methods of controlling toner concentration attempt to maintain a specific ratio of toner to carrier in the developer mixture. However, as the mixture ages, due to prolonged rubbing of toner and carrier, the toner charge for a given toner concentration will change. Toner charge impacts development efficiency and, thus, impacts print quality. Accordingly, a method to minimize the impact of this aging is desired.